The phenomenon of fusion occurs when a substance receives heat from a source.
A substance is said to be crystalline when it melts abruptly at a certain temperature, while the substance does not crystalline gradually softens during melting, becoming pasty and then liquefying completely.
During fusion, a crystalline substance obeys the following laws:
1st Law: under constant pressure, the fusion of a crystalline substance takes place at constant temperature.
The fusion or solidification of a crystalline substance is one in which solid and liquid phases appear in the presence of each other.
2nd Law: for a given pressure, each substance has its melting temperature.
This means that the melting temperature of each substance varies with the change in pressure.
Most substances, during fusion, increase in volume. However, there are substances that behave inversely, such as water, bismuth, iron and antimony.
Substances that increase in volume during fusion, when they undergo increased pressure, have their temperatures increased, while those that decrease in volume, have their temperatures decreased, if there is an increase in pressure.
By Kléber Cavalcante
Graduated in Physics